Levitated micro-manipulator system

ABSTRACT

A method of propelling a magnetic manipulator above a circuit substrate includes arranging a magnetic manipulator on a diamagnetic layer on a surface of the circuit substrate, generating drive signals using a controller, and applying the drive signals to at least two conductive traces arranged in the circuit substrate below the diamagnetic layer. A circuit substrate to control movement of a magnetic manipulator has a diamagnetic layer on a surface of the substrate, and conductive traces arranged under the diamagnetic layer, the conductive traces arranged in a parallel line pattern in at least two separate layers.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/960,424 filed Dec. 3, 2010.

BACKGROUND

Magnet levitation has many possible applications. U.S. Pat. No.5,099,216, “Magnetically Levitated Apparatus,” to Pelrine, discussesmagnetically levitated robotic manipulators. The manipulators haveattached magnetically active components, such as permanent magnets, uponwhich magnetic forces are imposed by fields generated by electromagnets.The discussion also addresses stability and damping of the motion of therobotic manipulators, where the manipulators can move with six degreesof freedom.

U.S. Pat. No. 5,396,136, “Magnetic Field Levitation,” to Pelrine,discusses the use of a magnetic member having an array of magnets and adiamagnetic or other material having magnetic permeability of less thanone. The diamagnetic material acts as a base defining an area over whichthe magnetic member can levitate and be moved by external magneticforces.

These approaches generally rely upon an array of electromagnets toprovide the magnetic fields to act upon the magnetic robots. The arraysof electromagnets determine the regions upon which the robots can becontrolled by the fields generated by the electromagnets. While thesearrays provide reasonably precise control of the robots, they stillrequire electromagnets to provide the external forces that act on therobots. Another approach, discussed in U.S. Pat. No. 6,858,184,“Microlaboratory Devices and Methods,” uses a substrate having within itbiasing elements in conjunction with an array of drive elements abovethe substrate. The drive elements move the magnetic elements in thespace between the drive elements and the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a side view of a magnetic levitated manipulator system.

FIG. 2 shows an embodiment of a manipulator having a magnet array.

FIG. 3 shows a side view of a magnetic levitated manipulator systemcircuit substrate.

FIGS. 4-6 show an embodiment of trace patterns used to generate magneticfields.

FIGS. 7 and 8 show an alternative embodiment of trace patterns used togenerate magnetic fields.

FIGS. 9-12 show alternative embodiments of trace patterns used togenerate magnetic fields.

FIGS. 13 and 14 show an embodiment of a rotator trace pattern used togenerate magnetic fields.

FIGS. 15A-D show a circuit substrate having control patterns.

FIG. 16 shows an embodiment of a levitated microfactory.

FIG. 17 shows an embodiment a manipulator traversing zones in a zigzagpattern.

FIG. 18-19 show embodiments of boundaries and current flow in zones in agrid pattern.

FIG. 20 shows a drive circuit for a trace in a levitated manipulatorsystem.

FIGS. 21-28 show embodiments of microfactory system configurations.

FIGS. 29 and 30 show embodiments of end effectors.

FIG. 31 shows an embodiment of an end effector suitable forgravity-assisted tilting.

FIG. 32 shows an embodiment of a multiple substrate magnetic levitatedmanipulator system.

FIG. 33 shows an embodiment of a magnetic levitated manipulator systemhaving flexible circuit substrates.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIG. 1 shows a side view of an embodiment of a levitated manipulatorsystem 10. The system has a circuit substrate 12 in which reside circuittraces 16 and 22 to carry current. In this example, circuit trace 22carries current or is energized. The current travels in trace 22 flowinginto the page. The resulting magnetic field acts upon the magnet 18,also referred to as a manipulator. The manipulator 18 will move toposition 20 to align the magnetic dipole moment or magnetization of themanipulator to the field generated by the energized trace 22. In FIG. 2,magnet 18 has a magnetization horizontal and to the right. Themagnetization may also be in different directions, such as vertically upor down, in which case it will still respond to energized trace 22 butsettle to a different equilibrium location relative to energized trace22 (to align with the vertical field from trace 22 rather than thehorizontal field). The circuit substrate 12 may include mechanical stopssuch as 15 that allow the magnets to be mechanically stopped at desiredpositions, which may simplify control. The circuit substrate 12 may alsoinclude sensors such as 17 that sense the positions of the manipulatorsusing inductive feedback, optical sensing, etc. For example, the opticalsensing could be accomplished by optical sensors in the layers of thesubstrate with a hole allowing light to reach the sensor as shown bysensor 19. When a magnet or part of the manipulator structure crossesover the hole, causing a break in the light, the optical sensor wouldrespond.

A diamagnetic layer 14 defines the region over which the manipulatorwill levitate, producing a lift force that levitates the manipulator 18.By controlling the current in the various traces in the circuitsubstrate 12, one can cause the manipulator to move and perform tasks.By combining manipulators, the circuit substrate, and a controller tocontrol the application of current, one can coordinate the movements ofmanipulators to perform useful tasks. A wide variety of physical tasksare possible, including transport of materials, both solid and liquid,assembly of materials through application of adhesive and otherprocesses, sorting of materials, quality control assessments of materialproperties. These and other similar independent tasks are referred to asunit operations.

Further, higher levels of coordination and control at a system level arepossible that will result in the fabrication of complex components, orsome other useful industrial process. This coordination is similar tofull scale factory automation, possible at a micro scale through theembodiments discussed here. This full system of coordinated manipulatorsas a microfactory of levitated manipulators, or a levitatedmicrofactory. An example of a levitated microfactory will be discussedlater with reference to FIG. 16.

The manipulators will generally consist of one or more magnets arrangedtogether. In one embodiment the manipulators consist of a central magnetand four outer magnets. The poles and arrangement of these magnets mayachieve many effects. For example, the manipulators may be configured torepel other manipulators in a same plane of motion, such as a centralmagnet with canceling poles on the outer sides configured to cause themagnetic moment of the manipulator to be zero and to repel othersimilarly configured manipulators. Alternatively or in addition to theabove, the manipulators may have a zero net magnetic dipole moment toreduce the interaction with larger scale external magnetic fields suchas the earth's magnetic field. When levitated, the manipulators can movewith six degrees of freedom, three translational along the x, y and zaxes, and three rotational in pitch, yaw and roll.

In one embodiment shown in FIG. 2, the manipulator may consist of anarray of magnets. In the embodiment of FIG. 2, the center magnet with anorth pole is 1×1 mm, and the south pole cancelling magnets are 1×0.25mm. In one embodiment, the 1×1 mm and 1×0.25 mm magnets are 0.4 mmthick. These magnets may be grade 50 neodymium-iron magnets bondedtogether such as with epoxy. This particular configuration serves merelyas an example. In an alternative configuration, for example, the centermagnet may again be 1×1 mm, with the 4 canceling magnets being 0.75×0.33mm. In one embodiment, the 1×1 mm and the four 0.75×0.33 mm magnets are0.4 mm thick. Many kinds of arrays can be made and used, such as acheckerboard geometry having no net magnetic moment. A nine magnetcheckerboard array has a net magnetic moment and will repel a similarlyoriented nine magnet array. Magnetic shielding may also minimizemanipulator-manipulator magnetic interactions to allow close packing ofmanipulators.

Magnet arrays can also be connected such as using rigid lightweightmaterials such as rods and wires with adhesives. The magnetic behaviorof the connected manipulators depends on the nature of the connection(rigid or compliant) and the position of one array relative to theother. In one embodiment, for example, a first array using the magneticconfiguration shown in FIG. 2 is rigidly connected using 0.3 mm graphiterods with cyanoacrylate adhesive to a second identical array so that thebottom of the two arrays are parallel. Both arrays are oriented the sameway with this embodiment, and the offset distance of the rigidconnection is chosen so that both arrays experience identical magneticforces from repeating trace patterns such as those described below.

The manipulators move by reacting to the magnetic fields generated bycurrent in the traces on the circuit substrate. The circuit substratemay consist of one of many alternatives, including a printed circuitboard, a ceramic substrate, a semiconductor wafer, etc. No limitation isintended and none should be implied to any particular configuration ormaterial for the circuit substrate. FIG. 3 shows an embodiment of such asubstrate. In this embodiment, the circuit substrate 12 has four layersof conductive traces, typically copper, 32, 30, 28 and 26, separated byinsulating layers such as 36. The insulating layers 36 will typicallyhave minimal thickness, and the entire region of layers from 32 through26 will have minimal thickness as well. The lower layers will generallyhave lower gain, where gain is defined as the magnetic field gradient atthe top surface of conductive layer 24 per unit of current. Permanentmagnets, and therefore the manipulators, are moved by the magnetic fieldgradients. The lower gain of the lower traces may be compensated byraising the current in those traces as desired.

In one embodiment for example, the insulating layers 36 are 0.002″ thickand the conductive layers 32, 30, 28, and 26 use copper that is 0.0028″thick (sometimes referred to as 2 oz copper in the printed circuit boardindustry). In this embodiment, the trace widths are typically 0.010″wide and the currents are 0.25 A, 0.33 A, 0.48 A, and 0.70 A for layers26, 28, 30, and 32, respectively. As described below, negative currentsof similar magnitude can be used for quadrature drive to move the robot.Other values of current can, of course, be used, and higher currents canbe used to generate higher forces while lower currents reduce heatingand make the robot more likely to levitate above rather than slide alongthe surface.

Between the bottom circuit layer 32 and the connection layer 34, alarger insulating layer 38 resides. In one experiment, the innerinsulation layer 38 had a thickness of 1 millimeter or greater. Theconnection layer 34 connects to the conductive trace layers by way ofvias through the inner insulation layer 38 as well as between traces andthe insulating layers in the upper region of the substrate. In oneembodiment, the via connections were routed to the edge of the board.

The diamagnetic layer 14 resides on a first surface of the circuitsubstrate 12. As discussed above, the diamagnetic layer provides thelifting force that levitates the manipulators. In order to provide moreprecise control over the fields that cause the manipulators to move, aconductive layer 24 may reside over the diamagnetic layer to provideeddy current damping. Unlike the inner conductive layers which havepatterns of traces, the current damping layer will typically havecomplete coverage of the diamagnetic layer. The thicknesses ofdiamagnetic layer 14 and conductive layer 24 depends on the size of themanipulators and magnets, with larger manipulators and magnets generallyrequiring thicker layers.

In one embodiment using the magnetic array shown in FIG. 2 with a1×1×0.4 mm central magnet and 0.75×0.33×0.4 outer magnets, thediamagnetic layer 14 is made using a sheet of polished pyrolyticgraphite 0.5 mm thick, and the conductive layer is polished copperapproximately 0.012 mm thick. In some embodiments the manipulators donot fully levitate above the diamagnetic and conductive layers butrather slide on the surface. In other embodiments using sliding motion,the diamagnetic layer can even be eliminated. However, even when themanipulator is not levitated, a diamagnetic layer 14 exerts adiamagnetic force pushing the manipulator away from the surface, therebyreducing the effective friction by reducing the normal forces even inthe case of sliding motion. In one embodiment, a second very thin layer(0.025 mm thick) of diamagnetic graphite (not shown) is on top of theconductive layer 24 to further reduce friction.

Although FIGS. 1 and 3 show a relatively flat circuit substrate 12, itwill be understood that circuit substrate 12 can curved concave, convex,or in other complex shapes using circuit fabrication means known in theprior art. For example, circuit substrate 12 may be made using flexcircuit fabrication processes known in the prior art, or it may be madedirectly on a curved object using processes such as inkjet-printedcircuits. In some cases insulation layer 38 can be made very thin oreliminated entirely to enhance mechanical flexibility of the circuit.Connection layer 34 can also be eliminated in some embodiments by makingconnections off to the side of the magnetically active regions usingvias and contact pads known in the prior art.

In order to control the manipulator using the control zones over whichthe manipulators move, each layer of the circuit substrate has a patternof repeating traces which may be connected together by vias or directlyconnected. FIGS. 4-6 show an embodiment of an arrangement of the vias.In one embodiment, layer 26 from FIG. 3, the first conductive layer, hastwo parallel line patterns 40 and 41 offset one half the distance of thetrace-to-trace distance in each pattern shown in FIG. 4. For example, afirst parallel line pattern may have 1 mm spacing between traces in thepattern, with a second parallel line pattern being offset 0.5 mm fromthe first pattern. While the patterns have connections at the ends ofthe lines to the next line or lines in the pattern, the majority of thetrace lengths in this pattern consists of parallel lines.

Vias such as 43 are used to cross over into the second layer 28 fromFIG. 3 at points where the two patterns would otherwise touch in layer26. These vias form a sort of ‘underpass’ to allow the traces 41 toremain in their patterns but avoid contact with traces 40. The traces inFIG. 4 may be called x traces because they would typically be used tomove the manipulator in the x or horizontal direction shown in thefigure.

FIG. 5 shows a similar pattern for the y, or vertical direction ofmotion as drawn, traces. The second conductive layer 28 from FIG. 3 hastwo parallel line patterns 44 and 46 offset from each other one half ofthe distance between traces. Vias such as 48 provide connection to thefirst conductive layer 26 to provide crossover connections, using layer1, for parallel line pattern 44. FIG. 6 shows the combined via patternsof the first and second layers. While the term ‘pixel’ typically means‘picture element,’ or the smallest portion of an image, these combinedpatterns will be referred to as pixels. They are generally laid out in apixilated pattern, very similar to those of display elements. A pixelcan drive a single manipulator, or, if it is large enough, can drivemany manipulators in parallel where all the manipulators on the pixelwould move simultaneously in unison.

FIGS. 7-8 show an alternative embodiment of the trace patterns used togenerate magnetic fields. FIG. 7 shows an X pixel 50 that uses a similaroffset pattern as the pixels shown in FIGS. 4-6. However, in thisinstance the two offset patterns used for the X pixel 50 are in separatelayers. This eliminates the cross-over vias, but requires more layers,since the Y pixel will also require two layers for its offset patterns,resulting in use of four conductive layers.

Because of a need to cancel some fields at pixel boundaries, one mayrequire ‘flipped’ versions of the X and Y patterns. For example, FIG. 7shows a combination of an X pixel 50, similar to FIG. 4, and thevertically flipped version Xf, 52. Note that at the boundary betweenthese pixels 50 and 52, the traces of the two pixels come in closeproximity to each other as the parallel line pattern for each must turnhorizontally a short segment to make the next vertical trace. Theseshort horizontal segments can interfere with vertical motion if theycreate an unwanted magnetic field. However, by making the horizontalsegments for pixel 50 line up in close proximity with the horizontalsegments from pixel 52 but with opposite currents, the unwanted magneticfields from horizontal segments in an X direction pattern areeffectively canceled between the two pixels. In the exploded portion ofthe diagram, the arrows indicate the directions of the current in thedifferent traces, with only the top layer of traces shown. As seen here,the current in the vertical traces align, and the current in thehorizontal traces travel in opposite directions, resulting incancellation between them.

Similarly, the Y pixel 54, similar to that of FIG. 5 has a flippedversion Yf 56. These variations, of X+Y, X+Yf, Xf+Y and Xf+Yf combine toform a unit which can be thought of as an aggregate pixel that can movethe manipulator in both x and y directions. Vias can be used to connectthrough the circuit substrate for external connections on connectionlayer 34 in FIG. 3. This unit can be tiled throughout the circuitsubstrate as needed to control the manipulators. The externalconnections on the bottom connection layer 34, by suitable connectionsto a current source, can provide electrical current to drive the tracesin the pixels. The external connections can also be jumpered to connectpixels in series or parallel, to provide groups of pixels with commoncontrol. The currents through their respective traces are thenidentical, or, if desired, reversed polarity depending on theconnection.

FIGS. 9-12 show another alternative embodiment of trace patterns. FIG. 9shows an example of a symmetric zig-zag line pattern 70 formed in thefirst conductive layer for the drive traces. The zig-zag line pattern,formed from zigzag traces, is symmetric in that the height and width, L,of the local squares within the pattern are equal. The corners of thelocal squares may need to be angled to provide the necessary clearanceto the other squares in the pattern. The first layer has connectors,such as 72. The same zig-zag line pattern is used, only offset, forlayers 2 and 3.

For example, in FIG. 10, the zig-zag line pattern 70 of FIG. 9 has beenrepeated on trace layer 26 (see FIG. 3). The pattern 74 in FIG. 10,located on trace layer 28 (see FIG. 3), has been offset one half thesquare length L (see FIG. 9) horizontally relative to zig-zag linepattern 70. In the zigzag pattern shown in these diagrams, themanipulator will move in whichever direction the traces are offset. Thetraces actually run in a zigzag pattern at 45 degrees relative to the xand y directions shown in FIG. 10. In the parallel line patterns of theprevious FIGS. 4 to 8, the manipulator will move perpendicular to thesequentially actuated traces as described below. By contrast, thepattern 74 of FIG. 10, acting in conjunction with pattern 70, will causethe manipulator to move in the X direction shown by the axis. FIG. 11shows that the zigzag pattern has been offset vertically as well, aspattern 78. Pattern 78, acting in conjunction with pattern 70, willcause the manipulator to move in the Y direction shown by the axis.

FIG. 12 shows the resulting pattern. The zig-zag line pattern 70 of FIG.9 has been repeated in the second and third conductive layers but offsetone half of the length of the side of the nominal squares formed by thezigzag traces. The pattern 74 for the second conductive layer, forexample, has been offset one half the square length horizontally. Thepattern 78 for the third conductive layer has been offset one half thesquare length vertically. The second and third conductive layers havetheir own connections, 76 and 80 respectively, that allow connection toa current source to energize the traces in the pattern.

One may also expand the basic pattern of FIG. 9 and rotate it by 45degrees to provide the capability of rotating the manipulators as theylevitate. FIG. 13 shows an example of a rotator pattern 82. This patternmay reside in layer 4. FIG. 14 shows the combined layers and theresulting pattern of pattern 70 from the first layer, pattern 74 fromthe second layer, pattern 78 from the third layer and the rotatorpattern 82 in the fourth layer.

In one embodiment, the rotator pattern 82 is aligned to the symmetriczig-zag line pattern 70 by making the rotator pattern 82 squares be2^(0.5)=1.414 times the size of the squares in the symmetric zig-zagline pattern. The rotator pattern 82 in this embodiment aligns thesquare corners of the rotator pattern 82 with the corners of the squaresin every other diagonal in symmetric zig-zag line pattern 70. Thealigned corners for rotator pattern 82 and symmetric zig-zag linepattern 70 can be used to rotate suitably designed magnet arraymanipulators in this embodiment. In particular, a manipulator using anarray of 4 equal-size square magnets with canceling polarities, whichwould appear to have the north and south poles in a checkerboard fashionwhen viewed from above, can be rotated this way. In one embodiment eachof the 4 magnets has dimensions 1 mm×1 mm×0.4 mm, using a pattern withsquare size L=1 mm (see FIG. 9). The rotation for this embodiment can beaccomplished by driving a quadrature pattern of electrical currentsdescribed below using layer 1 and the rotator pattern on layer 4. Inanother embodiment the rotator pattern would reside under the XY viapattern discussed above to perform rotations. Typically, the rotatorpatterns combined with the above patterns will cause suitably designedmanipulators at specific locations to rotate.

In another option multiple different trace patterns can be used. Forexample, circular and curved traces could be used as will be discussedin more detail below. FIGS. 15A-15D show a resulting circuit substrate,such as a printed circuit board, having a rectangular x-y pattern and acircular pattern.

In FIG. 15A in the x-y pattern 90, the first layer shown in FIG. 15Acontains the parallel line pattern 91 having a known trace-to-tracedistance with connections 92. The second layer shown in FIG. 15Bcontains the parallel line pattern 93 offset from layer 1 vertically byhalf the trace-to-trace distance of the first layer with connections 94.When these two patterns are laid on top of each other, the pattern 93would appear just below pattern 91 in the gaps of pattern 91.

The third layer shown in FIG. 15C contains the parallel line pattern 95rotated 90 degrees relative to the first layer pattern 91, the thirdlayer having connections 96. The fourth layer contains the parallel linepattern 97 rotated 90 degrees relative to the first layer pattern, andoffset horizontally half the trace distance from the third layer patternwith connections 98. When the third and fourth layers patterns are laidon top of each other, the pattern 97 would appear in the gaps of pattern95, similar to that of the first two layers, but rotated 90 degrees.

Trace patterns can also have curvature. The circuit substrate of FIGS.15A-15D has a circular pattern 100. The first layer pattern 101 has thesame trace-to-trace distance as the parallel line patterns, but run in acircular pattern and has connections 102. The second layer pattern 103overlaps the first layer pattern over 90 degrees of the circle. In thisparticular embodiment, the quarter of the circular pattern beingoverlapped from layer 1 lies in the upper left quadrant of the circleoriented on the page, near the second layer connections 104. If thesetwo drawings were laid on top of each other, one would not be able tosee the second layer pattern 103 separate from the first layer pattern101.

The third layer pattern 105 of FIG. 15C does not follow the circularpattern of the first and second patterns; instead the pattern crossesthe circles formed by the first layer in an in and out radial pattern,with connections 106. The spacing between the in and out traces isnominally the same spacing as the magnet size in one embodiment, thoughthe curved nature of the pattern means the inner part has slightlynarrower trace spacing than the outer trace spacing. The fourth layerpattern 107 with connections 108 of FIG. 15D follows the same pattern asthe third layer but is rotated 1.5 degrees, in this embodiment, suchthat each radial line of the fourth layer passes midway between tworadial lines of the third layer. In another embodiment, the fourth layerpattern is rotated such that its traces move approximately ½ magnet sizealong the circle relative to the corresponding third layer traces.Again, the spacing is nominal and actually varies slightly from innerpart of the trace to the outer part. This circular pattern causes themanipulators to travel in a circle, similar to a racetrack. When layer 3is laid on layer 4, the traces from layer 4 are visible in the gaps oflayer 3.

The above discussion merely demonstrates that curved patterns onmultiple layers are possible. Trace patterns may be in any type ofpattern desired, including grids, parallel line patterns, squarepatterns, curved patterns or any combination thereof.

Having seen the structures within the circuit substrate, the discussionnow turns to how those structures are employed to move the manipulators.To provide context for the discussion, and with no intention to limitthe microfactory to any particular configuration, FIG. 16 shows an8-zone work surface that includes a liquid deposition and cleaningstation 112, an input station 114, multiple output stations 116, arecirculating buffer zone 118 and a staging zone 120. The work surfacemay have multiple manipulators moving in unison, and sets ofmanipulators in alternate zones. The driving of the manipulators must becoordinated. The manipulators can use extensions, attached to themanipulators, with various end effectors (tools) known in the prior art.In some cases the end effectors can be simple sharp or blunt tips.

In the zigzag and parallel line traces, quadrature drive signals areused to create magnetic forces that propel the manipulator. The twotraces are driven with a quadrature time-dependence of currents; thetraveling wave will cause the manipulator to move perpendicular to thequadrature-driven traces of the parallel line pattern. For example, aparallel line pattern of two interleaved traces, discussed above such astraces 40 and 41 in FIG. 4, that vary spatially in the y-direction willmove the manipulator in the x-direction. Using a notation in which (+,+) denotes a phase where each of the traces is driven with positivecurrent, first layer and second layer or (L1, L2), (−, +) would denotethat L1 is driving negative and L2 is driven positive and so forth. Aquadrature drive to move perpendicular to the parallel line traces isthen given as the time sequence of currents: (+, +), (−, +), (−,−) and(+,−). Reversing the sequence reverses the direction of motion and onecan use microstepping to achieve intermediate locations between thediscrete steps. Microstepping may be achieved using intermediate values.For example, to achieve a position between (+, +) and (−,+), one mightdrive the currents as (0, +), where the 0 represents the average current(zero) in Trace 1 between the two states. Alternately, microstepping canbe achieved using a high speed time sequence of states that average tothe desired state, such as a high speed oscillation between states (+,+)and (−,+).

With this method of control, the currents must be switched faster thanthe manipulator can respond to individual sets of currents so that themanipulator's inertia effectively averages the high speed sequence. Themanipulator can move in the perpendicular motion using the other sets oftraces such as those in the third layer (L3) and the fourth layer (L4).When moving in the x-direction, one would typically hold the y traceswith fixed current to prevent unwanted y motion during movement in thex-direction. Similarly, when moving in the y-direction, the current inthe x traces would typically be held fixed. However, it is also possibleto move in arbitrary diagonal directions using trace patterns such asshown in FIG. 6 by suitably driving quadrature currents in both x and ytraces simultaneously. Although the description here discusses moving inthe x and y direction using quadrature drive, the magnitude of the tracecurrents can also be used for control, such as by pulling part or all ofa levitated manipulator closer to the surface of diamagnetic layer 14using a higher current and hence stronger magnetic force.

FIG. 17 shows an example of the timing using quadrature drive signals ina parallel line pattern of traces that create magnetic forces thatpropel the manipulator 18 across a zone boundary 122. In this drawing,only one set of traces to move in the vertical or Y direction on thepage are shown for clarity. The other set of traces, the X traces, canbe driven similarly when X motion is desired. The quadrature traces Aand B for zone 124, and the corresponding traces A′ and B′ for zone 126,are controlled independently. As manipulator 18 moves from zone 124 intozone 126, the trace A in zone 124 and trace A′ in zone 126 are drivenwith the opposite currents from each other, with the same happening inthe two B traces. In this manner, the magnetic patterned of peaks andtroughs in the magnetic field formed by trace A in zone 124 can belocally extended into zone 126 with reverse current in trace A′, andsimilarly for the magnetic patterns formed by traces B and B′.

FIG. 18 shows another example in which some or all of the work surface130 is divided into smaller zones, such as 132, each with a horizontaldrive trace oriented vertically such as 134 and a vertical drive tracesuch as 136 oriented horizontally. The different zones control segmentsof the drive traces, and can be connected to control electronics and apower source using, for example, vias that connect to the bottom of thecircuit board. For ease of discussion, these zones will be numbered 1-7horizontally and vertically. For example, the manipulator 18 in thisexample is holding at position (4, 4). Generally, a manipulator is heldin a steady state position by having the current in the horizontal andvertical traces set up a preferred magnetic position of the localmagnetic energy minimum of the manipulator 18 in the field generated bythe currents.

For example, with the manipulator 18 shown in FIG. 18 and letting (x,y)denote the x and y position of the center of the manipulator 18 anddenoting the zone at location (a,b) by Z(a,b), running current frombottom to top as shown by arrow 138 through the zones Z(x−1,y)=Z(x−1,y−1)=Z(x−1,y+1)=Z(x−1,y−2)=Z(x−1, y+2) causes a force to theright of the grid. In the example of holding the manipulator at (4,4),the positive current will pass through (3,2), (3,3), (3,4), (3,5) and(3,6). A negative current is then run from top to bottom to create anequal force to the left of the grid, shown by arrow 140 through zonesZ(x+1, y)=Z(x+1, y−1)=Z(x+1, y+1), Z(x+1, y−2)=Z(x+1, y+2), or onehorizontal trace to the left of the holding point, starting two zonesabove and ending two zones below the holding point.

Similarly, current is run through the horizontally oriented, verticalcontrol traces 142 and 144, with the positive current running from leftto right in arrow 144, one vertical step up from the holding point. Thiscauses a force to the bottom of the grid. Negative current then runsfrom right to left along trace 142, one vertical step down from theholding point, creating a force to the top of the grid. By settingcurrents in suitable zones in this way, the preferred magnetic positionis determined. Manipulators with other magnetic geometries will havedifferent sets of currents to set the preferred position.

Using these principles, then, one can move the manipulator to anadjacent zone by controlling the current in adjacent traces as shown inFIG. 19. By setting the current in the vertically oriented, horizontaltrace 146 at (4,6) through (4,2) to some positive level, the current attrace 138 at (3,2) through (3,6) to zero, the current in trace 140 at(5,2) to (5,6) to zero, and the current in trace 148 at (6,2) to (6,6)to the negative current of the current in trace 146, the manipulatorwould move over one zone from the position in FIG. 18. The current intrace 148 prevents the manipulator from advancing further. Traces 142and 144 can keep the same currents they had in FIG. 18. Traces 142 and144 do not move the manipulator in this case but they act as magneticguides to keep the manipulator in the desired Y or vertical position onthe page.

The manipulator could be moved to other adjacent zones in the horizontalor vertical directions, as well as diagonally by moving the manipulatorhorizontally and vertically together. Rotations can also be achieved byselectively driving zones and current segment so as to impart a torqueon different parts of the manipulator.

In the grid traces, each of the traces in each zone is drivenindependently by a two-dimensional array of electronics below thetraces. For each trace there could be four transistors to drive thecurrent in the trace in both directions, such as the “H-bridge”configuration of 4 transistors known in the prior art as one way toarrange the transistors, with other circuit elements such as flip-flopsto hold the state of the current. The act of setting current values forthe grids of zones is similar to that of setting pixel values in atwo-dimensional light-emitting diode display. The controller would sendthe current values to the electronics during each time cycle.Alternatively, the control would send only the values that change fromone cycle to the next, and the electronics would modify the currentvalues for the appropriate zones.

The designs shown here have either zigzag alternating traces, or thegrid pattern having horizontal and vertical drive traces described as aparallel line pattern. Each design has its own advantages anddisadvantages. The zigzag patterns require fewer connections and aresimpler to control. One could tessellate the zigzag pattern in a mannersimilar to the parallel line pattern. This would allow the zigzagpattern to control as many manipulators as the grid layout. The zigzagpattern only requires one trace with current to hold the manipulator(s)in a fixed location, whereas the grid or parallel line pattern requirestwo traces (one x, one y) carrying current to hold a fixed location. Thegrid layout has much more flexibility and finer control but requiresmore signals and more connections.

The application of the current to the traces may be achieved in manydifferent ways. FIG. 20 shows an example of a switch and driver circuitfor the traces. A controller 160, mentioned previously, controls thetiming and application of current to the traces as discussed above. Therelay 162, such as a solid state relay, drives positive current to aparticular trace and relay 164 drives the negative current. Each relaycan be switched using an input current of 5-10 milliamps from controller160 in this particular embodiment, and one terminal of the relay'soutput is connected to a positive or negative voltage supply. Thisexample shows voltage supplies of 12 volts, but other voltages may beused depending upon the system configuration, materials and technologiesused.

A resistor 166 may limit current as a safeguard in the situation wherethe potentiometer 168 may be incorrectly set. In the particular exampleof FIG. 20, with the voltages and current supplies, the total resistanceshould be approximately 10-40 ohms depending on the resistances of thetraces the circuit is driving. The inductor 170 represents the traceitself on the circuit board, with ground 172 for the power supply. Theresistor as well as other circuit elements for control may be includedin the circuit substrate.

In operation, the system may use analog currents for optimal control.The discussion up to this point has focused on control being on theregions defined by the traces. However, the manipulators may move fromone separate control region to another, traveling across regions of nocontrol. This may be referred to as ballistic motion. The manipulatormotion within one zone is built up and then ‘flown’ across a region ofno control to another region of control. This motion may occur betweenzones on the same circuit substrate, or even from one circuit substrateto another, across a gap.

In other types of motion, one region may have the manipulatorslevitated, and another region may have the manipulators in contact withthe surface. However, generally having the manipulators levitate willcause less wear and allow for more freedom of movement. The diamagneticor current damping layer shown in FIG. 3 may be polished to allow themanipulators ease of movement. The surface of the layer should have aroughness less than a levitation distance of the manipulators.Non-levitated regions can be used to securely turn off power to thesystem without the manipulators levitating or floating to uncontrolledlocations in the power off state. In another embodiment, the levitationsurface can have shallow depressions to hold the manipulators inspecified locations in the power off state. Since the manipulators canmove freely throughout the system, a power shutdown routine can be usedto move the manipulators to secure power off locations before thesystem's power to the traces is turned off

Having seen the overall system for the manipulators to be moved andcontrolled, the discussion now turns to applications of thesemanipulators in various factory type settings. FIGS. 21-28 show variousconfigurations to perform various processes in factory-like systems. InFIG. 21, the circuit substrate 12 has a controller 160 connected tocontrol the current in the traces. The manipulator 18 has an endeffector 182, essentially the working piece of the manipulator. Thisparticular end effector has a probe or dip tip 184 upon which is aliquid 186. The liquid 186 may be a liquid to be deposited or may alterthe surface adhesion energy of the tip 184 to allow it to pick up piecesand place them on the work object 190. The liquid may be picked up fromthe reservoir 180 and may act as an etchant, a depositable material,etc. By controlling the current in the traces, one can cause themanipulator to move to the reservoir 180 and pick up the liquid and thenoperate on the work object 190.

FIG. 22 shows an alternative configuration of the manipulator. In thissituation, the work object 190 has too great a height for themanipulator to levitate above it. Instead, the end effector 182 in thisembodiment has an extension length that allows the manipulator to workover the edge of the work object. The end effector can only reach adistance on the interior of the work object equal to the extensionlength.

A similar limitation exists in the configurations where the work object190 is beyond the floor of the system, shown in FIG. 23. The circuitsubstrate 12 is arranged adjacent the work object 190, and themanipulator can hover next to it with its extension arm 182. Again, theend effector can only reach a distance on the interior of the workobject equal to the extension of the extension length.

As discussed above many manipulators can operate simultaneously. In theconfiguration of FIG. 24, multiple manipulators 18 and 200 can work onthe work object 190. The circuit substrate 12 has holes such as 194which the manipulators can operate. The manipulator then pivot downs tothe depth of the floor. In this and other embodiments, the manipulatorscan have different end effector extension to reach different parts ofthe work object 190.

In FIG. 25, the work object lies above the circuit substrate 12. Itwould be secured against gravity or reside on the underside of someother object. The end effector would be oriented to allow themanipulator to perform tasks above it. Similarly, in FIG. 26, the workobject is to the side of the circuit substrate 12, on which the endeffector could be performing pick and place on the work object 190,which may translate up and down from the circuit substrate to allowcomplete coverage.

In an alternative arrangement, shown in FIG. 27, the work object 190could reside under the circuit substrate 12 which can provide a liftingforce to the manipulator 18. The manipulator 18 would be levitated bythe circuit substrate as a ceiling over the work object 190.

FIG. 28 shows an example of the manipulator going from one surface toanother. The circuit substrate 12 levitates the manipulator 18 and movesit towards the second surface 210. As the manipulator nears the secondcircuit substrate 210, the control of the manipulator moves to thecircuit substrate 210. The traces controlling manipulator 18 in circuitsubstrate 12 may be turned off to facilitate control transfer to circuitsubstrate 210. In one embodiment, high current pulses of 0.8 to 1.0 Aare used in the traces of circuit substrate 210 to further facilitatecontrol transfer. With the movement in the vertical direction, themanipulator will typically have to rest on the surface of the circuitsubstrate 210 in order to counteract gravity. This merely demonstratesthe flexibility of the system and the ability to move manipulatorsaround to perform tasks.

As indicated by FIG. 28, systems can consist of multiple circuitsubstrates 12 in various orientations. For example, the circuitsubstrate 12 may be duplicated many times in parallel to the one shownin FIG. 26 to allow manipulators to work on work object 190 at multiplepoints. In other cases multiple circuit substrates can be used toincrease performance, such as placing a one circuit substrate 12 belowmanipulator 18 and a second circuit substrate close but above it. Thiswould be analogous to the circuit substrate 12 shown above themanipulator 18 in FIG. 27 but with a circuit substrate below manipulator18 rather than work object 190 below it. By driving manipulator 18 withtwo rather than one circuit substrate, peak force and peak speed of themanipulator 18 are increased. Three-dimensional arrays of circuitsubstrates can be configured as shown in FIG. 32, with manipulators 18moving freely between the circuit substrates using methods such as shownin FIG. 28. The system may also use flexible circuits for circuitsubstrate 12 to make bent or curved paths, as shown in FIG. 33

In systems employing multiple circuit substrates 12, the multiple boardscan be fixed or in some embodiments they may be replaceable to configurethe system in different ways to achieve different desired functions. Forexample, the system may use a “motherboard” approach known in the priorart, with individual circuit substrates 12 plugged into the motherboardin a replaceable manner.

It will be appreciated from the above description that manipulators 18can operate on circuits 12 in any orientation. Indeed, given sufficientcurrent in the traces of circuits 12 the manipulators 18 can evenoperate while the orientation is actively changing, such as when circuitsubstrates 12 are in a portable hand-held device or when circuitsubstrates 12 are attached to a robot wrist which can changeorientation. In one embodiment, via patterns such as those shown inFIGS. 26 and 28 were used with trace currents of 0.8 A in conductivelayers 26 and 28 were used for a device that could be operated while itsorientation was being changed by hand.

The tasks performed by the manipulators may depend in part upon the endeffectors and their configurations. For example, the end effector 182 ofFIGS. 21-28 used liquid either as a deposited material, an etchant or asan adhesive to attach material or other pieces to the end effector. FIG.29 shows a ‘fork’ or “shovel” type end effector useful to move materialsaround in multiple directions allowing transportation of materialsacross the work surface. FIG. 30 shows a “pusher” end effector thatallows the material to be pushed in one direction. In one example, theshovel end effector on the end of one manipulator may place the materialin front of the broom end effector of another manipulator, allowing thebroom end effector to push the material up against a work object.

As noted above, with suitable programming, manipulators can betranslated and rotated to translate and rotate their attached endeffectors to perform various desired tasks. To tilt about an axisparallel to the plane of diamagnetic layer 14, for example, the tracecurrents can be driven to repel the magnets in one part of manipulator18 while attracting other magnets in other parts of manipulator 18.Manipulator 18 can thus be made to rotate or tilt about an axis parallelto diamagnetic layer 14, where “yaw” is defined as a rotation about anaxis perpendicular to the local plane of circuit substrate 12, and“roll” and “pitch” would be tilt directions of rotation. Even simplercontrol strategies may be used for tilt in many cases using the addedmass of the end effector in conjunction with gravity.

FIG. 31 shows a simple example analogous to the configuration shown inFIG. 23. Manipulator 18 with end effector 182 moving on circuitsubstrate 12 approaches work object 190 in a powered-on state in FIG. 31a. To tilt the end effector 182 down to touch work object 190, power isturned off In this embodiment, end effector 182 has enough mass relativeto manipulator 18 that gravity will tilt the manipulator 18 and itsrigidly attached end effector 182 into a “tilt-down” state by rotatingaround the tilt axis 230 extending into the page shown in

FIG. 31 b. Tilt axis 230 would generally coincide with at least twopoints on manipulator 18 to define an axis of rotation. A single pointon manipulator 18 can also be used in some cases but, depending on themass distribution, a single point may cause some component of rotationabout an axis perpendicular rather than parallel to the diamagneticlayer 14.

To tilt up, power is applied to circuit substrate 12 and the magneticforces are sufficient to re-orient manipulator 18 and end effector 182back to the “tilt-up” state. Mass can be added or subtracted from thestructure of end effector 182 to achieve reliable tilt-down and tilt-upstates relative to the available magnetic forces from circuit substrate12. With proper mass balancing on a low friction diamagnetic layer 14,the manipulator 18 can even be made to translate parallel to the planeof circuit substrate in a low-current mode, with a high-current modebeing used for tilt-up operations. In one embodiment, the low-currentmode was 0.25 A, 0.33 A, 0.5 A, and 0.7 A for conductive layers 26, 28,30, and 32 in circuit substrate 12 (see FIG. 3) and the high currentmode used 0.8 A, 0.8 A, 0.5 A, and 0.7 A for the high-current mode forconductive layers 26, 28, 30, and 32 respectively.

In this manner, a microfactory system can be provided that allowsmultiple manipulators to be controlled on the surface of a circuitsubstrate. The circuit substrate can be manufactured according tostandard manufacturing techniques. The controller provides precisecontrol of the manipulators to perform tasks on a work object.

It will be appreciated that several of the above-disclosed and otherfeatures and functions, or alternatives thereof, may be desirablycombined into many other different systems or applications. Also thatvarious presently unforeseen or unanticipated alternatives,modifications, variations, or improvements therein may be subsequentlymade by those skilled in the art which are also intended to beencompassed by the following claims.

1. A method of propelling a magnetic manipulator above a circuitsubstrate, comprising: arranging a magnetic manipulator on a diamagneticlayer on a surface of the circuit substrate; generating drive signalsusing a controller; and applying the drive signals to at least twoconductive traces arranged in the circuit substrate below thediamagnetic layer.
 2. The method of claim 1, wherein the conductivetraces are arranged in a pattern such that two interleaved sets oftraces are spatially offset in a first direction and applying the drivesignals in a time sequence causes the manipulator to move parallel tothe first direction.
 3. The method of claim 1, wherein the conductivetraces are arranged in a zigzag pattern spatially offset in a firstdirection and applying the drive signals in a time sequence causes themanipulator to move in the first direction.
 4. The method of claim 1,wherein applying drive signals to the conductive traces comprisesapplying the drive signals in discrete steps, wherein a discrete stepresults from applying one of a positive current or a negative current toeach of the conductive traces independently.
 5. The method of claim 6,wherein applying drive signals comprises microstepping in which currentin one of the traces is set to zero to achieve intermediate locationsbetween the discrete steps.
 6. The method of claim 1, wherein applyingthe drive signals comprises: driving traces in a first zone to generatea first current in the first zone; driving traces in a second zone togenerate a second current in the second zone; and using the first andsecond currents to create a continuous magnetic field pattern betweenthe first and second zones.
 7. The method of claim 1, wherein applyingthe drive signals comprises: applying a positive current in a firstdirection parallel with the surface of the circuit substrate on one sideof a particular position; applying a negative current in a seconddirection parallel with the surface of the circuit substrate and in adirection opposite the first direction on a second side of theparticular position; applying a positive current in a third directionparallel with the surface of the circuit substrate on a third side ofthe particular position; and applying a negative current in a fourthdirection parallel with the surface of the circuit substrate and in adirection opposite the third direction on a fourth side of a particularposition, causing a manipulator to remain stationary at the particularposition.
 8. The method of claim 1, wherein generating drive signalscomprises generating quadrature drive signals.
 9. A circuit substrate tocontrol movement of a magnetic manipulator, comprising: a diamagneticlayer on a surface of the substrate; and conductive traces arrangedunder the diamagnetic layer, the conductive traces arranged in aparallel line pattern in at least two separate layers.
 10. The substrateof claim 9, wherein the parallel line pattern comprises an interleavedpattern.
 11. The substrate of claim 10, wherein the interleaved patterncomprises a first conductive layer having two interleaved patterns,wherein a second parallel line pattern is offset spatially from a firstparallel line pattern in a first direction.
 12. The substrate of claim10, wherein the second parallel line pattern is offset spatially fromthe first parallel line pattern one half of a trace-to-trace distance inthe first parallel line pattern.
 13. The substrate of claim 9, furthercomprising a second layer having vias, the vias arranged to makeconnections out of the first layer in regions where the first and secondparallel line patterns would otherwise make contact.
 14. The substrateof claim 13, further comprising a third layer, the third layer havingthird and fourth parallel line patterns, rotated ninety degrees from thefirst and second parallel line patterns, the fourth parallel linepattern offset spatially from a third parallel line pattern.
 15. Thesubstrate of claim 9, wherein the conductive traces are arranged in azigzag pattern.
 16. The substrate of claim 15, wherein the zigzagpattern comprises: a first zigzag pattern in a first layer of thecircuit substrate; a second zigzag pattern in a second layer of thecircuit substrate, the second zigzag pattern being offset spatially in afirst direction from the first zigzag pattern; a third zigzag pattern ina third layer of the circuit substrate, the third zigzag pattern beingrotated ninety degrees from the first zigzag pattern; and a fourthzigzag pattern in a fourth layer of the circuit substrate, the fourthzigzag pattern being offset spatially in a second direction from thethird zigzag pattern.
 17. The substrate of claim 16, further comprisinga rotator pattern having corners aligned with alternating corners of thefirst zigzag pattern.